Oven and electric heater therefor



May 27, 1924.

F. GRAF OVEN AND ELECTRIC HEATER THEREFOR Filed Nov. 9. 1920 2 Sheets-Sheet 1 QWMMV a a f 1 X U i wa "MG 1v I .d $7 W Z i J Q May 27, 1924. 1,495,685

F. GRAF OVEN AND ELECTRIC HEATER THEREFOR Filed Nov. 9. 1920 2 Sheets-Sheet 2 Patented May 27, 1924.

PATENT oFFica FRANZ em, 01' BAD, SWITZERLAND.

OVER AND ELECTRIC HEATER THEREFOR.

Application filed November 9, 1920. Serial 110. 422,844.

ing)ovens and the electrification thereof. 10

no object of the invention is to convert existing fuel heated baking ovens into electrically heated ovens without interfering with the existing fuel heating arrangements, so that the oven can be heated by either 15 means singly or by the combination of both nmeans.

Another object of the invention is to make fuel heated ovens independent of the fuel employed should this become scarce or the to make the ovens inde endent of this heating by means of fue Another object of the invention is to save the capital cost of installing a new electrically heated oven in lace of the existing fuel heated oven by a apting the latter for electrical heating.

The accompanying drawings illustrate structures in accordance with the present invention.

In the drawings,

Figure 1 is a sectional view of a fuel heated oven in which electrical heating elements are situated within the baking space and also without,

Figure 2 is a sectional view of a tubular oven heated by steam pipes in which the electrical heating elements are situated within and without the baking space, and

Figure 3 is a sectional vlew of an oven in which the electrical heating elements situated without the baking space are located in the existing flues of the furnace.

Referring to Figure 1; the oven bottom a is supported on tiles 1) so that a hollow space forming a compartment 0 is obtained to receive electric heaters d. At the sides of the oven, flues or ducts e are provided through which the heated air from the compartment 0 can be passed into the oven space or chamber f, the tiles 6 being so arranged or formed as to rovide apertures through which the heated air can escape from the compartment 0 to the side flue or duct 6 and case of a breakdown of the electrical energy 3 price of same become too high, also in the in order to cause the heated air to enter the oven space or chamber f at the top guiding plates or partitions 9 having apertures h are provided.

The heating effect is further increased by the provision of additional heaters d (Figure 1) disposed in chambers e' in the bakin s ace at t e sides of the fiues or ducts e an t ese heaters d are arranged to be controlled either topether with the heaters d or se arately. n the ovens adapted to be used for several dafys the heaters d help to create a to heat or the baking space or chamber be ow it.

The complete enclosure of the electric heaters in heat storing material is of great advantage by makin the cheap waste power in the night availa le during the greater part of the day without having to use expensive day current during this period. By the provision of the side fines or ducts e the heat reaches the oven space or chamber f quickly so that the bottom a of the oven is also heated strongly from above and can therefore, if necessary, be made of considerable thickness; by this means not only burning of the contents of the oven is prevented, but the heat storage capacity is increased by utilizing the cheap night current.

The construction of an oven described renders an even baking possible and allows the current to be left on during baking and it is equally suitable for adapting existing fuel heated ovens thereto and for newly erected ovens.

For obtaining a uniform heat and especially in ovens having inclined interiors the heating elements are so designed as to be displaceable, for instance, in the longitudinal direction of the oven.

Referring to Figures 2 and 3. In the structure according to Figure 2, the outlet 77 for the heating gases is at the top of the furnace space r and into the latter, closed steam pipes s and a project in a known manner, a part of which serves for heating the bottom a of the oven spaces or chambers gand another part provides the top heat.

esides the electric heaters d, the heat from which is distributed uniformly over the upper part of each oven space or chamber 7'' by means of the steam pipe 8, further heaters 03 are located, below the steam pipes s, in the closed horizontal cross-flues formed in the oven structure, by means of which a uniform bottom heat is obtained in the oven spaces or chambers f. t is the fire grate. V

The construction of oven according to- Figure 3, is provided, additionally to the electric heaters d positioned in the oven spaces or chambers f, with a plurality of heating resistances (l; a ser1es of three s shown in Figure 3, which liein the horizontal portions of the heating flues c and c and serve for heatin the top and bottom brickwork of the bal ing spaces or chambers f; t is the fire-grate.

Ovens designed according to Figures 2 and 3 may be operated in various ways. They may be heated by fuel only, or by the electric heaters only, and in the latter case by either set of the resistance elements only, or heating by fuel and electricity conjointly. Further, by cutting in and out the heaters, by series or parallel arrangements and by series or parallel resistances, the heating current, the heating of the oven and the-time taken in obtainin the required heat for baking may be regulated.

By the constructions and arrangements set forth herein a more uniform and better distribution of the heating efi'ect is obtained 1. In fuel heated baking ovens the combination of electrical heating elements located within the baking space itself with electrical heating elements situated outside the bakin space.

2. In i iiel heated baking ovens using steam heating pipes the combination of electrical heating elements located within the baking space itself with electrical heating elements situated in close proximity to the steam heating pipes. 7

3. In fuel heated baking ovens the combination comprising steam heating pipes, flues situated at right angles to the longitudinal direction of the steam heating pipes, electrical heating elements situated within the said fines, and electrical heating elements situated within the baking space itself.

In testimony whereof I have signed my name to this specification.

FRANZ GRAF. 

